bug #14648 [Console] Fix first choice was invalid when using value (ogizanagi)

This PR was merged into the 2.7 branch.

Discussion
----------

[Console] Fix first choice was invalid when using value

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This PR solves the following issues encountered using question helper and choices questions:
- First choice was not selectable by value.
- ChoiceList with associative choices with mixed string and int keys has same issue with first choice.
- Fix inconsistency by always returning values as strings.

First point exemple:
![screenshot 2015-05-15 a 17 16 12](https://cloud.githubusercontent.com/assets/2211145/7655757/3344b39a-fb26-11e4-9fe7-0775616619bf.PNG)

Last two points are mainly edge cases. Indeed, if a QuestionChoice has something like :
```php
array(
    '0' => 'No environment',
    '1' => 'My environment 1',
    'env_2' => 'My environment 2',
    3 => 'My environment 3',
);
```
as choices, you will not be able to select the first choice and get an `InvalidArgumentException`:

```
There were 2 errors:

1) Symfony\Component\Console\Tests\Helper\QuestionHelperTest::testChoiceFromChoicelistWithMixedKeys with data set #0 ('0', '0')
InvalidArgumentException: Value "0" is invalid

2) Symfony\Component\Console\Tests\Helper\QuestionHelperTest::testChoiceFromChoicelistWithMixedKeys with data set #1 ('No environment', '0')
InvalidArgumentException: Value "No environment" is invalid
```

Moreover, even if you were able to select by value (`No environment`), you'll get an integer instead of a string:
```
Failed asserting that '0' is identical to 0.
```
For more consistency, the solution is to always return a string.

The issue does not exist in 2.6, as the `QuestionChoice::getDefaultValidator` handled things differently.

Commits
-------

03e4ab6 [Console] Fix first choice was invalid when using value

src/Symfony/Component/Console/Question/ChoiceQuestion.php

@@ -149,19 +149,19 @@ class ChoiceQuestion extends Question
                 $result = array_search($value, $choices);
 
                 if (!$isAssoc) {
-                    if (!empty($result)) {
+                    if (false !== $result) {
                         $result = $choices[$result];
                     } elseif (isset($choices[$value])) {
                         $result = $choices[$value];
                     }
-                } elseif (empty($result) && array_key_exists($value, $choices)) {
+                } elseif (false === $result && isset($choices[$value])) {
                     $result = $value;
                 }
 
-                if (empty($result)) {
+                if (false === $result) {
                     throw new \InvalidArgumentException(sprintf($errorMessage, $value));
                 }
-                array_push($multiselectChoices, $result);
+                array_push($multiselectChoices, (string) $result);
             }
 
             if ($multiselect) {

src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php

@@ -210,6 +210,76 @@ class QuestionHelperTest extends \PHPUnit_Framework_TestCase
         }
     }
 
+    /**
+     * @dataProvider simpleAnswerProvider
+     */
+    public function testSelectChoiceFromSimpleChoices($providedAnswer, $expectedValue)
+    {
+        $possibleChoices = array(
+            'My environment 1',
+            'My environment 2',
+            'My environment 3',
+        );
+
+        $dialog = new QuestionHelper();
+        $dialog->setInputStream($this->getInputStream($providedAnswer."\n"));
+        $helperSet = new HelperSet(array(new FormatterHelper()));
+        $dialog->setHelperSet($helperSet);
+
+        $question = new ChoiceQuestion('Please select the environment to load', $possibleChoices);
+        $answer = $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question);
+
+        $this->assertSame($expectedValue, $answer);
+    }
+
+    public function simpleAnswerProvider()
+    {
+        return array(
+            array(0, 'My environment 1'),
+            array(1, 'My environment 2'),
+            array(2, 'My environment 3'),
+            array('My environment 1', 'My environment 1'),
+            array('My environment 2', 'My environment 2'),
+            array('My environment 3', 'My environment 3'),
+        );
+    }
+
+    /**
+     * @dataProvider mixedKeysChoiceListAnswerProvider
+     */
+    public function testChoiceFromChoicelistWithMixedKeys($providedAnswer, $expectedValue)
+    {
+        $possibleChoices = array(
+            '0' => 'No environment',
+            '1' => 'My environment 1',
+            'env_2' => 'My environment 2',
+            3 => 'My environment 3',
+        );
+
+        $dialog = new QuestionHelper();
+        $dialog->setInputStream($this->getInputStream($providedAnswer."\n"));
+        $helperSet = new HelperSet(array(new FormatterHelper()));
+        $dialog->setHelperSet($helperSet);
+
+        $question = new ChoiceQuestion('Please select the environment to load', $possibleChoices);
+        $question->setMaxAttempts(1);
+        $answer = $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question);
+
+        $this->assertSame($expectedValue, $answer);
+    }
+
+    public function mixedKeysChoiceListAnswerProvider()
+    {
+        return array(
+            array('0', '0'),
+            array('No environment', '0'),
+            array('1', '1'),
+            array('env_2', 'env_2'),
+            array(3, '3'),
+            array('My environment 1', '1'),
+        );
+    }
+
     /**
      * @dataProvider answerProvider
      */